module

Apache mod_isapi Dangling Pointer

Disclosed
03/05/2010
Created
05/30/2018

Description

This module triggers a use-after-free vulnerability in the Apache
Software Foundation mod_isapi extension for versions 2.2.14 and earlier.
In order to reach the vulnerable code, the target server must have an
ISAPI module installed and configured.

By making a request that terminates abnormally (either an aborted TCP
connection or an unsatisfied chunked request), mod_isapi will unload the
ISAPI extension. Later, if another request comes for that ISAPI module,
previously obtained pointers will be used resulting in an access
violation or potentially arbitrary code execution.

Although arbitrary code execution is theoretically possible, a
real-world method of invoking this consequence has not been proven. In
order to do so, one would need to find a situation where a particular
ISAPI module loads at an image base address that can be re-allocated by
a remote attacker.

Limited success was encountered using two separate ISAPI modules. In
this scenario, a second ISAPI module was loaded into the same memory
area as the previously unloaded module.

Authors

Brett Gervasonijduck

Module Options

To display the available options, load the module within the Metasploit console and run the commands ‘show options’ or ‘show advanced’:

    msf > use auxiliary/dos/http/apache_mod_isapi
    msf /(i) > show actions
        ...actions...
    msf /(i) > set ACTION < action-name >
    msf /(i) > show options
        ...show and set options...
    msf /(i) > run
  
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